A compulsive and obsessive disorder where one is thoroughly engrossed with the song "Friday" by Rebecca Black. Symptoms may include singing the song on a Friday, watching the video on Youtube more than once, or putting a "like" on the song itself. Altogether dangerous and should be treated with a shot of reality that no one gives a crap about a song about a day of the week.
Guy 1: (listening to Friday on iPhone) man this is good. i love fridays even more now!
Guy 2: You need to see a doctor because I'm afraid you have Rebecca Black Disorder.